CLARITHROMYCIN SHOULD NOT BE USED IN PREGNANT WOMEN EXCEPT IN CLINICALCIRCUMSTANCES WHERE NO ALTERNATIVE THERAPY IS APPROPRIATE. IF PREGNANCYOCCURS WHILE TAKING THIS DRUG, THE PATIENT SHOULD BE APPRISED OF THEPOTENTIAL HAZARD TO THE FETUS. CLARITHROMYCIN HAS DEMONSTRATED ADVERSEEFFECTS OF PREGNANCY OUTCOME AND/OR EMBRYO-FETAL DEVELOPMENT INMONKEYS, RATS, MICE, AND RABBITS AT DOSES THAT PRODUCED PLASMA LEVELS 2 TO 17 TIMES THE SERUM LEVELS ACHIEVED IN HUMANS TREATED AT THE MAXIMUMRECOMMENDED HUMAN DOSES. (See PRECAUTIONS - Pregnancy.)

Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterialagents, including clarithromycin, and may range in severity from mild diarrhea to fatal colitis.Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C.difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxinproducing strains of C. difficile cause increased morbidity and mortality, as these infections can berefractory to antimicrobial therapy and may require colectomy. CDAD must be considered in allpatients who present with diarrhea following antibiotic use. Careful medical history is necessary sinceCDAD has been reported to occur over two months after the administration of antibacterial agents.If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need tobe discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotictreatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

There have been post-marketing reports of colchicine toxicity with concomitant use of clarithromycinand colchicine, especially in the elderly, some of which occurred in patients with renal insufficiency.Deaths have been reported in some such patients. (See PRECAUTIONS.)

For information about warnings of other drugs indicated in combination with clarithromycin, refer tothe WARNINGS section of their package inserts.